Towed vehicles weighing more than certain state regulated weights are required to have brakes which may be operated from the cab of the towing vehicle. In general, such vehicles as mobile homes, recreational trailers, and certain other towed vehicles such as boat trailers employ electrically-operated brakes and such type brakes have been in use for a number of years. Typical illustrations of such brakes are contained in U.S. Pat. Nos. 3,134,463 and 3,244,259.
Recently there has been a movement reflected by S.A.E. and Government regulations to require a greater usage of brakes on towed vehicles, extending the requirement to vehicles of lower weight than previously required and requiring in some instances that all wheels of the towed vehicles be equipped with brakes. The latter requirement is in contrast to past practices in which, for example, mobile homes having a total of six or eight wheels would have brakes on only two or four of them. The result is that there has currently appeared a substantially increasing need for electrically equipped brake assemblies. This, of course, is in turn bringing about significantly increased costs of such vehicles, particularly since existing type electrical brakes have a good many components and are fairly expensive to manufacture.
In addition to the substantial costs of existing type electrical brakes, it has been found that in many instances their operation has been less than satisfactory. For example, it has been found that balanced loading of brake lining against brake drums is not often achieved, resulting in a deterioration in available braking force. This problem exists with mechanical, hydraulic, and air-operated drum brakes as well and, accordingly, the present invention is directed to drum-type brakes in general.
Another common problem has been that excessive forces are concentrated on certain components of the operating mechanisms causing deformation or failure of components, resulting in complete or nearly complete brake failure.